Chlorpyrifos: A Broad-Spectrum Organophosphate Insecticide

Technical Introduction

Chlorpyrifos (IUPAC: O,O-diethyl O-(3,5,6-trichloropyridin-2-yl) phosphorothioate) is a widely used organophosphate insecticide for controlling chewing and sucking insect pests in agricultural and horticultural crops. It acts by inhibiting acetylcholinesterase (AChE), disrupting insect nervous system function.

• Mode of Action: Organophosphate acetylcholinesterase inhibitor (IRAC Group 1B), causing nerve overstimulation, paralysis, and death.

• Systemicity: Primarily contact and stomach poison, not highly systemic, but effective when ingested or contacted by pests.

• Target Spectrum: Effective against aphids, leafhoppers, thrips, caterpillars, beetles, termites, and soil pests.

Applications

• Field Crops:

  • Used on corn, cotton, soybean, rice, and wheat for pest control.

• Vegetables & Fruits:

  • Applied to tomatoes, peppers, potatoes, citrus, apples, grapes to manage chewing and sucking insects.

• Soil Treatment:

  • Controls soil-dwelling pests such as rootworms, wireworms, and grubs.

• Public Health & Forestry:

  • Occasionally used for termite management and mosquito larval control in water bodies.

Advantages

• Broad-Spectrum Efficacy: Controls both foliar and soil pests across multiple crop types.

• Fast Knockdown: Rapidly reduces pest populations after application.

• Flexible Formulations: Available as EC, WP, ULV, and granules for different application methods.

• Cost-Effective: Long history of use with proven efficacy at relatively low cost.

Specifications (Typical Parameters)

FAQ

Q1: How does Chlorpyrifos work on pests?
A: It inhibits acetylcholinesterase, causing accumulation of acetylcholine in nerve synapses, leading to continuous nerve firing, paralysis, and death.

Q2: Is Chlorpyrifos systemic?
A: No. It works primarily as a contact and stomach poison. Foliar pests ingest or contact it to be affected.

Q3: Can Chlorpyrifos be used during flowering?
A: It is highly toxic to bees. Avoid use during flowering and when pollinators are active.

Q4: Are there resistance concerns?
A: Yes. Resistance has been reported in aphids, whiteflies, and other pests. Rotation with insecticides from different IRAC groups is recommended.

Q5: Is Chlorpyrifos still widely used?
A: Its use is restricted or banned in many countries (EU, USA) due to environmental and human health concerns, but it is still used in some regions under regulatory guidelines.